You should earn rank by accumulating Rank Up points or some other scaled denominator other than GC Seals.

They should be totally separate. It appears to me that the developers are being lazy and reusing the same mechanism for rewards as they are for determining the procedure for achieving rank.

Elements like Mercenary rank made sense. I only cited it as an example.

I cited taxes as an example too.

You may be able to get GC Seals in exchange for Guild Marks that you have spent and not spent. That is my point.

The reference to rank being optional was a response to another's post, not yours, where they said: "Spend your seals wisely or grind some more. It's your choice"